In a field of medical activity, for example, there is a case where an infusion fluid such as blood, plasma, physiological saline, nutrition fluid and medical fluid is supplied into a living body. In such a case, for example, it is common that the infusion fluid is stored in an infusion fluid container such as bag and bottle that is hung by a stand, and is infused into a blood vessel of the living body through an intravenous drip cylinder, a roller clamp, an infusion fluid tube and a hypodermic needle that are connected to the infusion fluid container, or is supplied directly into a digestive organ of the living body through the infusion fluid tube, or is supplied orally into a mouth of the living body through the infusion fluid tube.
In most cases, the infusion fluid is stored at a relatively low temperature due to request for maintaining the quality, so that the infusion fluid is required to be warmed to about a temperature of the living body as rapidly as possible in a case where rapid supply of the infusion fluid is necessary, for example, in event of an emergency operation. To this end, there has been developed an infusion fluid warming apparatus for warming the infusion fluid to a suitable temperature, during process of rapidly supplying the infusion fluid as described above. Examples of such an infusion fluid warming apparatus are disclosed in Patent Document 1 and Patent Document 2. The infusion fluid warming apparatus disclosed in Patent Document 1 is a bag-shaped heat exchanger pack which has passages for guiding the infusion fluid and a warming medium so that the infusion fluid is warmed by the warming medium. The infusion fluid warming apparatus disclosed in Patent Document 2 has an arrangement in which the fluid is warmed while passing through a seat-like sealed passageway that covers a circumferential surface of a heating core.
[Patent Document 1] JP2002-102349A
[Patent Document 2] JP2000-502938A
However, since each of the above-described conventional infusion fluid warming apparatuses requires a device for circulating the warming medium or the heating core whose temperature is controlled, there is a case where the apparatus can not warm the infusion fluid in an emergency facility in transfer of a patient or in outdoors due to difficulty in obtaining a power source. On the other hand, it might be possible to use, as a source for heating the infusion fluid, a heating element made of a material that generates a heat by its reaction with oxygen contained in an air, or a heating element that generates a heat by reaction of quicklime with water. However, the heating element utilizing such an exothermic reaction does not have a function for rapidly warming the infusion fluid and maintaining the warmed infusion fluid at a constant temperature for a relatively large length of time. Thus, the heating element utilizing the exothermic reaction is unsuitable for warming the infusion fluid.
The present invention was made in the light of the background art discussed above. It is therefore an object of the invention to provide an infusion fluid warming apparatus capable of rapidly warming an infusion fluid even in a circumstance without availability of a power source and maintaining the warmed infusion fluid at a constant temperature for a relatively large length of time.